It found that more than one fifth (23 per cent) of those surveyed believed those older than 55 were less productive, and took more sick leave.
Randstad New Zealand manager Brien Keegan said these were "common misconceptions".
"In reality, productivity levels are comparable throughout the generations, and absenteeism is actually often lower in the 55 [and older] age group than among younger employees.
The survey also found that just 39 per cent of employers had active policies in place to attract people aged 55 years or older.
Mr Keegan said businesses needed to recognise mature workers had a lot to offer.
"Kiwis businesses stand to benefit if they take advantage of the knowledge and expertise older generations bring to the workforce.
"There is no reason for businesses to discount mature jobseekers and instead should be looking to them to add value to the business," he said.
Mr Keegan said it was important that mature workers knew they had a lot to offer an employer, most notably a wealth of knowledge and experience, which he said younger generations often could not compete with.
He said it was "critical" older workers sold their skills, knowledge and experience - but in order to be employable, they also needed to "continuously refresh their knowledge and upskill".
"The way in which we work and the skills needed in the workplace are constantly evolving.
"Older workers need to keep pace with the new skill-sets younger generations are bringing to the force."